The present invention relates to an image inputting apparatus such as scanner, facsimile and the like usable for an apparatus optically reading out letters or images described on medium such as paper.
The image inputting apparatus of the type mentioned above includes various types of scanner such as a card-type scanner which is usable in operative connection with an information processing unit such as portable information device such as electronic note, personal computer, personal word processor or the like and also includes an image reader generally comprising an image reading unit and an image processing unit.
For example, there is known a card-type scanner as a card-type image read-out memory device as disclosed in the Japanese Patent Laid-open (KOKAI) Publication No. SHO 64-5163. This card-type scanner is provided with a read-out section at a card central portion and the read-out operation is performed by slidingly scanning the card. Image data read out, through the scanning, is inputted into a memory section inside the card and is then outputted (displayed) to a dedicated output device through a card I/F, which is a dedicated device provided with a card throttle through which the card-type scanner can be inserted.
In recent days, an information processing unit provided with a card I/F has been developed by making compact a portable information device such as electronic note, personal computer, personal word processor or the like, whereby it becomes possible to directly display images read out by the scanner on a screen of the information processing unit.
In such conventional structure mentioned above, however, when performing the scanning operation while connecting the card-type scanner to the information processing unit and confirming the image data inputted by the card-type scanner, there is provided a problem that the whole body, except a connector, projects from a display device and also provided a difficulty for closely contacting a read-out surface of the scanner to a medium to be read out, further leading to a problem that a read-out operation while confirming the inputted image data cannot be precisely performed.
In view of the above problems, Japanese Patent Laid-open (KOKAI) Publication No. HEI 7-283910 provides an image reading device, which is composed of an image read-out module and a portable information equipment body, the image read-out module being integrally constructed of a sensor unit including an image sensor and a copy (medium) lightening means and a PC card interface unit, and the portable information equipment body being provided with an image display means and a PC card insertion unit. This image reading device is further provided with a fixing means for fixing the image read-out module to the portable information equipment body at a time when the image read-out module is inserted into the PC card insertion unit of the portable information equipment body to thereby read out (input) the image. In the image reading device of Japanese Patent Laid-open (KOKAI) Publication No. HEI 7-283910, however, since the image read-out module is merely fixed to the portable information equipment body, it is necessary to move the image read-out module and the portable information equipment body together with respect to the image read-out surface when the image is read out, thus being inconvenient in use.
Furthermore, in the conventional scanner of the type mentioned above, since an image reading direction can be freely selected, there is a case that an image may be reversed according to the image reading direction, thus also being inconvenient.
In another aspect, the image inputting apparatus is applied for an apparatus optically reading out letters or images described on a medium such as paper, converting the read-out images into electric signals which are then digitalized, and displaying and/or transferring the same.
Japanese Patent laid-open (KOKAI) Publication No.SHO 63-296557 discloses a conventionally known image read-out circuit means, which has a structure represented by a block diagram shown in FIG. 36, which comprises an image read-out unit 301, an A/D conversion unit 302 for converting analog signals of letters or images read out by the image read-out unit 301 into digital signals, a peak value storing unit 303 for detecting and storing a peak value (analog signal) of read-out values based on one line read-out of a copy to be read (inputted) and giving the peak value to the A/D conversion unit and an image processing unit 304 for binarizing (binary coding) the digital data from the A/D conversion unit 302 into whited ata and black data.
In this known image read-out circuit means, the peak value of the input data stored in the peak value storing unit is used for determining a dynamic range at the time of the A/D conversion in the A/D converter. Further, in the image processing unit, a reference value for the binary coding (binarization) is required. In this known circuit means, with reference to the peak value stored in the peak value storing unit, a threshold value as a reference for the binary coding judgement is determined.
According to the known circuit means mentioneda bove, since the threshold value is determined with reference to the peak value of the read-out values based on the one line read-out of the copy, in a case where large variation of the white data of the copy is caused by irregularity of the sensitivity of the sensor or lightening means, there may cause a case where the actual input white data becomes lower than the threshold value and, hence, is erroneously discriminated as black data and the threshold value cannot be stably produced. Thus, the binary coding or binarization processing of the image has not been accurately performed, providing a problem.
A primary object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art described above and to provide an image inputting apparatus which is capable of performing an easy and accurate image inputting operation and providing an improved structure therefor.
Another object of the present invention is to provide, in one aspect, an image inputting apparatus of a card-type scanner structure capable of easily reading images on a medium to be read and preventing the image from being reversely displayed due to a reading direction.
A further object of the present invention is to provide, in another aspect, an image inputting apparatus capable of accurately performing binarization (binary coding) even in a case of reading out a base portion (white portion) of the medium (copy) due to irregularity of sensor sensitivity or lightening condition in addition to easy maneuvability of an operator.
These and other objects can be achieved according to the present invention by providing, in one aspect, there is provided an image inputting apparatus to be used in combination with an information processing system, comprising an image reading unit and a PC card unit operatively connected to the image reading unit and the information processing system, the image reading unit comprising an image reading section for optically reading out an image on a medium to be read and converting a read-out image into an analog electric signal and a movement measuring section for measuring a moving amount of the image reading section moving on the medium, and
the PC card unit comprising an image signal processing section for processing the analog image signal from the image reading section, a read-out control section for performing a driving control of the image reading section in accordance with the moving amount from the movement measuring section and a PC card interface (I/F) section operatively connected to the read-out control section and the external information processing system so as to perform interruption and access to the information processing system, and the PC card unit having a structure in shape of card capable of being inserted into a pre-determined portion of the information processing system in a manner such that, when the PC card unit is inserted into the information processing system, the image reading unit is positioned outside the information processing system.
In preferred embodiments of this aspect, the PC card unit and the image reading unit are integrated together so that the image reading unit project outward the information processing system so as to be rotatable about an axis extending at least one of an extending direction of the PC card unit and a direction perpendicular to the extending direction.
The PC card unit and the image reading unit are composed of independent structures from each other, which are operatively connected through a connection means. The connection means comprises a flexible cable and a connector.
The image reading unit has a box-shaped structure and the connection means is accommodated in the box-shaped image reading unit.
The image reading unit further comprises an image signal amplifying section operatively connected to the image reading section for amplifying an analog image signal therefrom. The PC card unit further comprises a driving condition setting section operatively connected to the read-out control section for setting driving conditions for the image reading section.
The image reading unit is further provided with means for giving image read-out start/finish instruction to the read-out control section of the PC card unit. The box-shaped image reading unit is further provided detachably with a reading assisting means at a surface portion thereof to read out an image on the medium by moving the medium in front of the surface of the image reading unit on which the reading assisting means is mounted. The reading assisting means is composed of a pair of rollers disposed with a gap, which are rolled by passing the medium through the gap therebetween with substantially no load.
The PC card unit further comprises means for changing an order to image data to be read out in accordance with an image reading direction preliminarily set to the read-out control section.
The read-out control section performs image read-out control in accordance with an image read-out start/finish instruction from the information processing system.
According to this aspect of the present invention, when the image inputting apparatus of the card-type scanner structure is inserted into the information processing system, since the image reading unit including the image reading section and the movement (moving amount or distance) measuring section projects over the information processing system, the reading (inputting) process can be done while confirming the image on the display means of the information processing system with the card-type scanner being integrated with the information processing system, thus being convenient.
Since the projected image reading unit is constructed to be rotatable with respect to the PC card unit inserted into the information processing system, the display means can be directed to an operator regardless of the image scanning direction, and accordingly, the inputting operation can be done while confirming the reading image.
In the arrangement in which the PC card unit is independently formed from the image reading unit, which are operatively connected by the connection means, the image on the medium to be read can be read out at a portion remote from the information processing system by freely selecting the reading (scanning) direction.
In the arrangement provided with the analog signal amplifying section, fine or weak read-out image signal can be amplified, and hence, the image on the medium remotely positioned can be freely read out with a proper magnitude.
In the arrangement provided with the driving condition setting section, the read-out can be done even if the sensor disposed in the separate unit is changed freely in size.
In an arrangement in which the sensor of the image reading unit is a single dimensional line sensor, in the case where the reading direction of the sensor does not accord with the scanning direction of the card-type scanner, the read-out data has mirror image relationship and it is therefore necessary to change the data after the reading (inputting) process. According to the present invention, in such case, the read-out data order can be reversed by preliminarily inputting the reading direction of the card-type scanner to the control means to thereby always read out the correctly directed image data.
In the arrangement in which the read-out control is performed by the read-out start/finish instruction from the information processing system, the read-out processing can be done by the start/finish instruction from the information processing system while confirming the reading image displayed on the display means of the information processing system, thus realizing an improved maneuvability of an operator.
The start/finish instruction may be executed by the start/finish indicating section provided in the image reading unit, in such arrangement, when the PC card unit is independently disposed from the image reading unit, the improved maneuvability can be done with high accuracy even in the arrangement of the information processing system remote from the image reading unit.
In the arrangement of the read-out assisting means on the front portion of the box-shaped image reading unit, the reading (inputting) process can be done even if the medium to be read has a small size.
Many other advantageous effects and functions may be achieved by organic combination or modification of the above various embodiments in this aspect of the present invention.
In another aspect of the present invention, there is provided an image inputting apparatus comprising an image reading unit and an image processing unit operatively connected to the image reading unit,
the image reading unit comprising a sensor means for optically reading out an image on a medium to be read and an A/D conversion means for converting a read-out image into a digital electric signal, and
the image processing unit comprising an image processing section operatively connected with the image reading unit for performing a binarization processing of the image signal, a data storing section for storing inputdata representing white and black portions of a medium to be read, and a threshold value producing section for producing a threshold value in accordance with data from the data storing section and transferring the threshold value to the image processing section,
the threshold value producing section including a white bottom value detecting means for detecting a white bottom value as a minimum data in the input data of the white portion as a read-out reference and a threshold value calculating means for calculating the threshold value (S) by using the white bottom value (WB) detected by the white bottom value detecting means in accordance with the following equation:
S=xcex1xc3x97WB(0 less than xcex1 less than 1)xe2x80x83xe2x80x83(1)
(xcex1: coefficient for determining a threshold value).
In preferred embodiments of this aspect, the threshold value producing means further includes a black peak value detecting means for detecting a black peak value as a maximum value in the input data of the black portion as a read-out reference and the threshold value calculating means calculates the threshold value (S) by using the white bottom value (WB) detected by the white bottom value detecting means and the black peak value (BP) detected by the black peak value detecting means in accordance with the following equation:
S=xcex1xc3x97(WBxe2x88x92BP)+BP(0 less than xcex1 less than 1)xe2x80x83xe2x80x83(2)
(xcex1: coefficient for determining a threshold value).
The threshold value producing means may further include a black peak value storing means for storing data preliminarily set with a black peak value being a read-out reference and the threshold value calculating means calculates the threshold value (S) by using the white bottom value (WB) detected by the white bottom value detecting means and the black peak value (BP) stored in the black peak value storing means in accordance with the following equation:
S=xcex1xc3x97(WBxe2x88x92BP)+BP(0 less than xcex1 less than 1)xe2x80x83xe2x80x83(3)
(xcex1: coefficient for determining a threshold value).
The image processing unit further includes a level correction means for correcting a level of the input data from the image reading unit before transferring the data to the image processing section. The level correction means is composed of a shading compensation section.
The image inputting apparatus further comprises an area indication means for defining a usable area of the input data and transferring only data on a preliminarily designated area of the medium to be read as an input data to the threshold value producing section.
According to this aspect of the present invention, for example, in the embodiment represented by the equation (1), in a case where xcex1 is xc2xd (smaller than 1), for example, the threshold value obtained by this equation (1) is always less than the white bottom value, and accordingly, if the read-out value varies, the read-out image signal of the white portion is not lower than the threshold value and, hence, is hardly discriminated as black portion, which may be caused in the conventional technology.
Furthermore, in the embodiments represented by the equation (2) or (3), in a case where xcex1 is xc2xd (smaller than 1), for example, the threshold value obtained by this equation (2) is always less than the white bottom value and more than the black peak value, and accordingly, if the read-out value varies, the read-out image signal of the white portion is not lower than the threshold value and, hence, is hardly discriminated as black portion, and the black portion is never erroneously discriminated as white portion, which may be caused in the conventional technology.
Furthermore, the black peak value is preliminarily set as experimental value without inputting the black portion as reference value, and in such case, substantially the same functions and effects as those mentioned above can be attained through the equation (3).
In the arrangement provided with the shading compensation section, the dynamic range of the input data can be widened in the entire area of the sensor, thus being advantageous.
In the arrangement provided with the effective area indication section, noises or the like other than designated area can be eliminated.
Many other advantageous effects and functions may be achieved by organic combination or modification of the above various embodiments in this aspect of the present invention.
In a further aspect of the present invention, there is provided an image inputting apparatus comprising an image reading unit and an image processing unit operatively connected to the image reading unit,
the image reading unit comprising a sensor means for optically reading out an image on a medium to be read and an A/D conversion means for converting a read-out image into a digital electric signal, and
the image processing unit comprising an image processing section for performing a binarization processing of the image signal, a data storing section for storing input data from the image reading unit, a pixel value histogram distribution producing section for producing a pixel value histogram distribution in accordance with the input data, and a threshold value producing section for producing a threshold value in accordance with data from said pixel value histogram distribution producing section and transferring the threshold value to the image processing section for the binarization processing therein.
In preferred embodiments of this aspect, the image processing unit may further comprise a shading compensation section for performing a shading compensation to the input data from the image reading unit and said data storing section stores the thus compensated input data.
The threshold value producing section includes a white peak value detecting means for detecting a white peak value in the input data of the white portion of the medium to be read, a black peak value detecting means for detecting a black peak value in the input data of the black portion of the medium and a threshold value calculating means for calculating the threshold value (S) by using the white peak value (WP) detected by the white peak value detecting means and the black peak value (BP) detected by the black peak value detecting means in accordance with the following equation:
S=xcex1xc3x97(WPxe2x88x92BP)+BP(0 less than xcex1 less than 1)
(xcex1: coefficient for determining a threshold value).
The pixel value histogram distribution producing section produces the pixel value histogram distribution only on the basis of the input data with a defined range on a preliminarily designated one line.
The input data storing section stores a specified one line data of the medium to be read and the threshold value producing section produces a threshold value in accordance with the thus stored one line data. The input data storing section stores one line data per N lines (N:integer not less than 1) of the input data of the medium to be read and the threshold value producing section produces a threshold value in accordance with the thus stored line data.
According to this aspect of the present invention, the white (base) portion and the black (letter or image) portion can be correctly detected by providing the pixel value histogram distribution section.
That is, the pixel values (gray level) of the inputted data are distributed between the white (base) and black (letter) portion of the medium to be read. In general, the letter portion includes white portions between letters, and accordingly, the white pixel value is distributed in a certain ratio. Further, in the case of high optical resolution, the letter portion distribution also includes ink level of the letters in a certain ratio. Accordingly, the white (base) portion and the black (letter) portion can be correctly detected by providing the pixel value histogram distribution section.
Even in the case of the input data under the presence of the irregularity of the sensor sensitivity or lightening means, the white peak value and the black peak value of the input level of the medium to be read can be stored as reference values by way of the pixel value histogram distribution of the input data, and the threshold value can be produced by using such reference values, so that the obtained threshold values never exceed the white and black levels, thus always correctly performing the binarization (binary coding).
In this aspect, the shading compensation means may be also utilized as in the former aspect, and accordingly, the dynamic range of the input data can be widened in the entire area of the sensor, and in a case of a pseudo intermediate tone input level, correct processing can be always performed by the thus obtained threshold values.
In the arrangement of the effective area indication means, a medium to be read having a length shorter than the effective length of the image reading unit can be correctly read out and inputted and the threshold value can be calculated by using the white and black peak values obtained by the pixel value histogram distribution and the input data of a defined portion of a preliminarily designated one line. Accordingly, even in the case where portions (background) other than the pixel value range of the medium to be read are simultaneously inputted, the binarized (binary coded) threshold value can be produced.
In a case where the processing for producing the pixel value histogram distribution from the input data and obtaining the white and black peak values by way of software, much time and many processes are required. Then, such processing is separately performed from an actual read-out processing. One line reading of the medium is once performed separately from the required reading process and the most optimum single coded threshold value is determined. Thereafter, with the same kind of medium, the same binary coded threshold value is used to thereby prevent the delay of the reading processing from causing, thus performing the accurate binarization processing.
Furthermore, in a usual reading process, same kind of mediums are continuously read out, and particularly, in a case where a read out area is smaller than the medium size, the last stage of the medium reading process will includes the base portion and letter portion. Then, the input data is read out at the finish time of the reading, and in the next reading process, the pixel value histogram is proposed by the stored input data thus obtained and the white and black peak values can be hence obtained. According to such processes, the most optimum binarization can be performed.
Many other advantageous effects and functions may be achieved by organic combination or modification of the above various embodiments in this aspect of the present invention.